Automatic circuit breaker



July 31, 1956 c. H. JORGENSEN 2,757,258

AUTOMATIC CIRCUIT BREAKER Filed Feb. 21, 1952 70 w 54 32 f 64 II we INVENTOR.

CLARENCE H. JoeaE/vsEN. 78/ 5 zjiiag wm United States Patent 1 2,757,258 AUTOMATIC ClRCUIT BREAKER Clarence H. Jorgensen, East Rochester, N. Y., assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application February 21, 1952, Serial No. 272,750 10 Claims. (Cl. 200116) This invention relates to electric circuit breakers of the type that are automatically operable to break the circuit controlled thereby in the event that a current greater than that which can be safely carried by said circuit is passed therethrough.

Devices of this type are provided to prevent damage and are generally in the form of removable fuses which are burned out by an excess current. The burned out fuse is rendered useless and must be replaced before the circuit can be again closed. Frequently the transmission of excess current which causes the burning out of the protective fuse is caused by some very temporary condition which terminates immediately, but the fuse is permanently destroyed and the circuit can not be used again until a new fuse is substituted for that burned out.

Accordingly, an object of the present invention is to provide an improved automatic circuit breaker which will automatically open a circuit, if such circuit canies an excess current, but, will not be damaged by said excess current, and which may be rendered effective to reclose the circuit whenever said circuit is opened thereby.

A further object of the invention is to provide a circuit breaker having a member automatically movable to circuit opening position if an excess current is passed through said circuit and manually operable means for resetting said movable member in its normal position so as to reclose the circuit.

A still further object of the invention is to provide an automatic circuit breaker having a temperature responsive member automatically movable to circuit breaking position at a predetermined temperature and manually operable means for restoring said member to its circuit closing position.

An additional object of the invention is to provide an automatic circuit breaker having a member movable to circuit breaking position at a predetermined circuit temperature and means controlled by variations in ambient temperature operable to compensate for the efiect of such variations on the action of the circuit controlling device so that the latter is effective to break the circuit at the same circuit temperature, regardless of variations in the ambient temperature.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

in the drawings:

Fig. 1 is a plan view partly in section of a device constructed in accordance with the present invention.

Fig. 2 is a section on the line 2-2 of Fig. 1, with the parts in the normal or circuit making position.

Fig. 3 is a section on the same line with the parts in the circuit breaking position.

Fig. 4 is a sectional view of a modified form of the invention.

Fig. 5 is a fragmentary section on the line 55 of Fig. 4.

Fig. 6 is a section on the line 66 of Fig. 5.

The device disclosed herein, although applicable to control any electric circuit, was designed primarily to control the various circuits of an automotive vehicle, such as headlights, stoplights, parking lights, etc. and While in the drawings only two circuit breaking devices are employed, in actual use as many of the devices may be provided as there are circuits to control.

Referring to the drawings, the numeral 20 indicates a base or supporting plate of insulating material having holes 22 through which attaching screws are insertable for securing the circuit breaking device in any suitable position. Extending upwardly from this base, as seen in Pig. 2, and integral therewith are lugs 24 having rounded surfaces 26 adapted to be engaged by grooves 28 in a cover plate 30, the surfaces 26 and grooves 28 constituting detents to hold the cover plate in position, but permitting it to be easily removed if desired.

Mounted in the base plate 20 are two binding posts 32 and 34 to which the conducting elements of the circuit to be controlled by the automatic breaking means are adapted to be connected. Connected to the binding post 32 and held in position thereby between the head 33 of the binding post 32 and the base plate 20 is a bowed spring member 36 which tends to assume the position shown in Fig. 3, but when the circuits are closed, is prevented from doing so by means later described.

The spring 36, at its left end, is bent back upon itself as clearly shown in Figs. 2 and 3 and the bent end 36a of spring 36 forms one of the contacts of the circuit controlling devicc. Received between the two parts of the spring 36 and held in position by a rivet 40, or other suitable means, is a plate of insulating material 38 to which is secured a button 42 of insulating material. Obviously such button may be formed integrally with the plate 38, if desired. At the right end of the plate 38, as seen in Fig. 2, there is an opening 44 through which there extends a bimetallic strip 4-5. This strip, as shown, is wider below the plate 38 than above such plate and there are shoulders 48, shown in dotted lines in Fig. 1, below the plate 38. These shoulders are far enough below the plate when the parts are in the Fig. 2 position to permit movement of the parts to the Fig. 3 position, and the shoulders 8 may be omitted entirely, if desired. At the lower end of the strip 46, as shown in Fig. 2, the strip is bent at degrees and the bent part 50 of such strip is held in position against the base plate by bolt 52. Upon variations in temperature, the strip 46 is moved to the right or left, as seen in Fig. 2, moving the plate 38 and the bent end 36a of spring as, which constitutes one of the contacts of the circuit controlling device, to the right or left, depending on whether the temperature is increased or decreased.

Connected to the binding post 34 is a second contact member which is a bimetallic strip 54, bent at 90 degrees at the lower end, and the bent portion 56 thereof is held in position against the base plate by the binding post 34. The upper end of the strip 54 is bent to the right, as indicated at 58, and at temperatures below a predetermined temperature, this bent part 58 of the strip 54 serves as a latch to hold the parts in the position shown in Fig. 2, if the spring 36 and plate 38 are moved to that position. These parts are manually moved to such position by mechanism which will now be described.

The cover plate 5% has an opening in which plunger 60 of suitable material is slidable. The plunger is positioned within a cylinder 62 having tangs 64 which project through openings in the cover plate and are bent over, as shown in Fig. 2, to hold the cylinder 62 in position. The plunger 6!) has an enlarged head 66 which extends through an opening in the end of cylinder 62 to permit manual operation of the plunger. Positioned around the plunger 60 and between the plunger end the cylinder 62 is a spring 68, one end of which engages the cover plate and the other end of which engages a flange 70 on the plunger, to normally hold the plunger in its uppermost position, as seen in Fig. 2.

As shown in the drawings, there are two circuits controlling devices embodying the parts which have been described and which are designated generally as A and B. These might, for example, control the stop light and parking light circuitsof an automotive vehicle. It will be understood, however, that as many of these devices are desired may be supported by the base plate 20 to control as many separate circuits as necessary. All of the several circuit controlling devices may be fundamentally alike in construction, but may vary in specific details, for example dimensions, if the circuits controlled have different current carrying capacities.

As already stated, the spring 36 normally tends to assume the position shown in Fig. 3. In order that the circuit controlled by the position of spring 36 may be closed, the parts can be moved to the position shown in Fig. 2 by operation of the element 66. In this position of the parts the contact 36a is engaged by the bimetallic contact 54 so that the circuit which is controlled by these contacts can be closed. The spring 36 tends to separate these contacts but is prevented from doing so by the latching actionof the temperature responsive contact 54. If a current is passing through the circuit controlled by contacts 54 and 36a and the circuit temperature does not exceed a predetermined degree, the parts remain in the position shown in Fig. 2 and the circuit remains closed. If there is a short circuit or for other reasons an excess current is passed through the circuit which is sufficient to heat the contact 54 above a predetermined degree, the contact moves to the left sufiiciently to release the contact 36a and the parts assume the position shown in Fig. 3, breaking the circuit.

When this takes place, the element 66 can be moved to restore the parts to the Fig. 2 position and if the condition which caused the heating of contact 54 no longer exists, the parts will remain in the Fig. 2 position and the circuit will remain closed as before. If the defect is a permanent one and the heating of contact 54 continues, the parts will assume the Fig. 3 position when element 66 is released. If this occurs, it will be an indication to the operator that there is some permanent damage to the circuit which will have to be repaired before the circuit can be used.

In order to compensate for variations in atmospheric temperatures so that at all atmospheric temperatures which may be encountered, the force required to move the parts to the Fig. 3 position will be the same, the bimetallic element 46 is provided. When an increase in atmospheric or ambient temperature is effective to move the contact 54 slightly to the left, the thermostatic strip 46 also moves to the left. Upon decrease in ambient temperature the action is just the reverse. The movement of strip 46 with reference to that of contact 54 is such that the force required and, therefore, the degree of heat necessary to move contact 54 to a position to release contact 36a so as to permit movement of the parts to the Fig. 3 position, is the same at whatever ambient temperature may be encountered during operation. in other words, the excess current which will elfect opening of the circuit is the same at high or low atmospheric temperatures.

If this compensating means was not provided, the circuit temperature would have to get higher at some air temperatures, in order for the circuit to be automatically opened, than would be necessary at other air temperatures, which is not desirable. The provision of the compensating means causes the circuit to be automatically opened at the same circuit temperature regardless of variations in ambient air temperature.

The modified form of the device shown in Fig. 4 is substantially the same in function and differs only in slight structural details. Instead of securing the plate 38 to a contact spring such as 36, the plate 38 has a projecting portion 72 which is received within the upper end of an ordinary coiled spring 74 positioned between the plate 3-8 and the base plate Ztl. The spring 74- is not a conducting element, but instead, the plate 38 has a separate contact g '76 riveted thereto and a conducting wire 78 connects this contact with a metal washer 8t), clamped between the head of the binding post 32 and the base plate, in conducting contact with said binding post. In this modification upward movement of the right end of plate 38 must be limited or the spring 80 might effect disengagement of the plate from the thermostatic element 46. To this end the element 46 has a slot 82 through which the plate 38 extends, such plate having a neck 84- which is received in the slot, while a head 86 and shoulders 88 at opposite sides of the neck, prevent disengagement of the parts 38 and 46. In assembling the device the plate 38 is turned 90 degrees from the position shown, the head 86 is moved through the slot in the element 4-6 and the plate 38 is then turned back to the position shown.

While the embodiments of the present invention as herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. In an automatic circuit breaker having a base of in sulating material, a pair of binding posts supported thereby to which the conducting elements of the circuit controlled by said circuit breaker are adapted to be connected, a resilient contact member connected to one of said binding posts, a second resilient contact member connected to the other of said binding posts and normally engaging said first contact member to hold it in circuit closing position, said second contact member being so constructed as to release said first contact member and permit separation of said contact members and opening of the circuit when an excess current is passed through said contact members, manually operable means for moving said first contact member to its initial position for reclosing the circuit and temperature responsive means operable to con trol the force exerted by said second contact member to hold the first contact member in circuit closing position in order to maintain said force substantially constant regardless of variations in ambient temperature.

2. In an automatic circuit breaker having a base of insulating material, a pair of binding posts supported thereby to which the conducting elements of the circuit controlled by said circuit breaker are adapted to be connected, a resilient contact member connected to one of said binding posts, a second resilient contact member connected to the other of said binding posts and normally engaging said first contact member to hold it in circuit closing position, said second contact member being so constructed as to release said first contact member and permit separation of said contact members and opening of the circuit when excess current is passed through said contact members and temperature responsive means operable to control the force exerted by said second contact member to hold the first contact member in circuit closing position in order to maintain said force substantially constant regardless of variations in ambient temperature.

3. In an automatic circuit breaker having a base of insulating material, a pair of binding posts supported thereby to which the conducting elements of the circuit controlled by said circuit breaker are adapted to be connected, a resilient contact member connected to one of said binding posts, a second resilient contact member connected to the other of said binding posts and normally engaging said first contact member to hold it in circuit closing position, said second contact member being responsive to temperature variations in the circuit and movable to permit separation of said contact members and opening of the circuit when a predetermined circuit temperature is reached, and means responsive to ambient temperature for controlling the force exerted by the second contact member on the first contact member to hold the latter in circuit closing position.

4. In an automatic circuit breaker having a base of insulating material, a pair of binding posts supported thereby to which the conducting elements of the circuit controlled by said circuit breaker are adapted to be connected, a resilient contact member connected to one of said binding posts, a second resilient contact member connected to the other of said binding posts and normally engaging said first contact member to hold it in circuit closing position, said second contact member being responsive to temperature variations in the circuit and movable to permit separation of said contact members and opening of the circuit when a predetermined circuit temperature is reached, and means controlled by ambient temperature and operative to maintain the force exerted by said second contact member on the first contact member to hold the latter in switch closing position by a substantially constant force regardless of variations in ambient temperature.

5. In an automatic circuit breaker having a base of insulating material, a pair of binding posts supported thereby to which the conducting elements of the circuit controlled by said circuit breaker are adapted .to be connected, a resilient contact member connected to one of said binding posts, a second resilient contact member connected to the other of said binding posts and normally engaging said first contact member to hold it in circuit closing position, said second contact member being responsive to temperature variations in the circuit and movable to permit separation of said contact members and opening of the circuit when a predetermined circuit temperature is reached, means responsive to ambient temperature for controlling the force exerted by the second contact member on the first contact member to hold the latter in circuit closing position and manually operable means for moving said first contact member to initial position in order to reclose the circuit when the temperature is below said predetermined temperature.

6. In an automatic circuit breaker having a base of insulating material, a pair of binding posts supported thereby to which the conducting elements of the circuit controlled by said circuit breaker are adapted to be connected, a spring connected to one of said binding posts and forming a contact member, said spring normally tending to move to a circuit opening position, a temperature responsive member connected to the other of said binding posts and normally engaging said spring to hold it in circuit closing position, said temperature responsive member being movable to release said spring when a predetermined circuit temperature is reached to permit opening of the circuit, and a second tmperature responsive member responsive to variations in ambient temperature and operatively connected to said spring, said second temperature responsive member being operative to cause the force exerted by said first thermostatic member to maintain the circuit closed, to be maintained substantially constant during variations in ambient temperature.

7. In an automatic circuit breaker having a base of insulating material, a pair of binding posts supported thereby to which the conducting elements of the circuit controlled by said circuit breaker are adapted to be connected, a spring connected to one of said binding posts and forming a contact member, said spring normally tending to move to a circuit opening position, a temperature responsive member connected to the other of said binding posts and normally engaging said spring to hold it in circuit closing position, said temperature responsive member being movable to release said spring when a predetermined circuit temperature is reached to permit opening of the circuit, and a second temperature responsive member responsive to variations in ambient temperature and operatively connected to said spring, said second temperature responsive means being etfectiva upon changes in ambient temperature to move said spring in the same direction and to substantially the same extent as the first temperature responsive member is moved, whereby the force effective to hold the circuit 75 2,458,804

closed is maintained substantially constant upon variations in ambient temperature.

8. In an automatic circuit breaker having a base of insulating material, a pair of binding posts supported thereby to which the conducting elements of the circuit controlled by said circuit breaker are adapted to be connected, a spring connected to one of said binding posts and forming a contact member, said spring normally tending to move to a circuit opening position, a temperature responsive member connected to the other of said binding posts and normally engaging said spring to hold it in circuit closing position, said temperature responsive member being movable to release said spring when a predetermined circuit temperature is reached to permit opening of the circuit, a second temperature responsive member responsive to variations in ambient temperature and operatively connected to said spring, said second temperature responsive means being efiective upon changes in ambient temperature to move said spring in the same direction and to substantially the same extent as the first temperature responsive member is moved, whereby the force effective to hold the circuit closed is maintained substantially constant upon variations in ambient temperature and a manually operable member operative when actuated to engage said spring and restore it to its switch closing position in order to reclose the circuit when the circuit temperature drops below said predetermined degree.

9. In an automatic circuit breaker having a base of insulating material, a pair of binding posts supported thereby to which the conducting elements of the circuit controlled by said circuit breaker are adapted to be connected, a spring engaging the base and supporting a member of insulating material having a contact secured thereto, said contact being electrically connected to one of said binding posts, a temperature responsive member connected to the other of said binding posts and normally engaging said contact to effect closing of the circuit, said temperature responsive member being movable to efiect separation of the contacts and opening of the circuit when a predetermined temperature is reached, and a second temperature responsive member responsive to variations in ambient temperature and operatively connected to said insulating material, said last named member being eflective to cause the circuit to be held closed by a substantially constant force regardless of variations in ambient temperature.

10. In an automatic circuit breaker having a base of insulating material, a pair of binding posts supported thereby to which the conducting elements of the circuit controlled by said circuit breaker are adapted to be connected, a spring engaging the base and supporting a member of insulating material having a contact secured thereto, means other than said spring for connecting said contact to one of said binding posts, a temperature responsive member connected to the other of said binding posts and normally engaging said contact to effect closing of the circuit, said temperature responsive member being movable to efiect separation of the contacts and opening of the circuit when a predetermined temperature is reached, and a second temperature responsive member responsive to variations in ambient temperature and operatively connected to said insulating material, said lastnamed member being efiective to cause the circuit to be held closed by a substantially constant force regardless of variations in ambient temperature.

References Cited in the file of this patent UNITED STATES PATENTS 1,891,015 Rich Dec. 13, 1932 1,899,558 Cohn et al. Feb. 28, 1933 1,954,588 Frank et al Apr. 10, 1934 2,147,754 Rivers Feb. 21, 1939 2,191,588 Sattler Feb. 27, 1940 Sundt Jan. 11, 1949 

